Underwater divers and firefighters rely on breathing air supplied by self-carried tanks of pressurized breathing air. The pressure of the breathing air in a tank is indicative of the amount of breathing air remaining in the tank. Analog gauges are typically provided on a tank, but such gauges can be difficult to read/monitor during a dive due to water turbidity, position of the gauge, etc. An additional or alternative approach is the provision of an emergency light that is lit when a tank's pressure reaches a predetermined low level. However, an emergency light does not convey any gauge information. Furthermore, if the emergency light and/or its triggering system experience a failure, the tank's emergency warning capability is lost.